I'm not sure what you mean by "those people", but the actual cutoff where you start having problems with people being extremely bored comes well before you hit

I'm not sure what you mean by "those people", but the actual cutoff where you start having problems with people being extremely bored comes well before you hit one in a million; it's closer to one in a thousand, in my experience. Which means that the NYC public schools (the subject of this conversation, recall) have ~1000 kids like that right now. Now their various "gifted" programs do take more kids than that; the bar for such things is often at the 95th percentile, not the 99.9th.